Retirement Savings Calculator: Will Your Savings Last?

How the result is calculated

The calculation has two stages: saving up, then drawing down.

Grow your savings to retirement. Your current savings and your monthly saving earn the "return before retirement" until the retirement age you enter. Each deposit goes in at the end of the month, and the yearly return is turned into a monthly rate that compounds to exactly the figure you enter. The monthly saving stays the same in dollars every year. It does not rise with pay or prices.
Show that balance in today's money.
Today's money = balance at retirement ÷ (1 + inflation) ^ years
Find the monthly gap. Your other income pays for part of your spending. Savings cover the rest.
Needed from savings = monthly spending − other monthly income
Both are entered in today's money, so the gap is raised with inflation to prices in your first year of retirement.
Draw down month by month. Each month the gap is taken out at the start of the month and what is left earns one month of the "return in retirement". Once a year the withdrawal steps up with inflation. The calculator stops when the balance cannot cover a full month, or when you reach 100.

The returns and the inflation rate are assumptions, not forecasts, and you can change all three. The result is an estimate. Investment returns are not guaranteed, all investments carry some risk, and savings that are invested can lose value.

Worked examples

Each example uses a 6% return before retirement, 4% in retirement and 2.5% inflation. None of these is a forecast.

A 40-year-old saving $500 a month

Has $60,000 saved, plans to retire at 67, wants $3,500 a month and expects $1,800 a month of other income, all in today's money.

Savings at age 67$681,976
The same in today's money$350,126
Spending wanted a month, today's money$3,500
Other income a month, today's money$1,800
Needed from savings a month, today's money$1,700
Needed from savings a month at age 67 prices$3,311
Savings last untilage 86 and 11 months

The same person with no other income

Everything is the same except the other income is $0, so savings must cover the full $3,500 a month.

Savings at age 67$681,976
The same in today's money$350,126
Spending wanted a month, today's money$3,500
Other income a month, today's money$0
Needed from savings a month, today's money$3,500
Needed from savings a month at age 67 prices$6,817
Savings last untilage 75 and 11 months

A 55-year-old catching up

Has $150,000 saved, saves $1,000 a month, retires at 67, wants $4,000 a month and expects $2,200 a month of other income.

Savings at age 67$509,777
The same in today's money$379,048
Spending wanted a month, today's money$4,000
Other income a month, today's money$2,200
Needed from savings a month, today's money$1,800
Needed from savings a month at age 67 prices$2,421
Savings last untilage 87 and 6 months

The first two examples show why the other income box matters. The same savings last many years longer when part of the spending is paid from somewhere else.

How long savings last, by balance and monthly withdrawal

Read across from the balance you expect at retirement to the amount you would take from savings each month in your first year. The withdrawal then rises with inflation every year.

Retiring at 67, 4% yearly return in retirement, withdrawals rising 2.5% a year. The age shown is your age when the savings run out. Assumptions for illustration.
Balance at 67	$2,000 a month	$3,000 a month	$4,000 a month	$5,000 a month	$6,000 a month
$250,000	Age 78	Age 74	Age 72	Age 71	Age 70
$500,000	Age 92	Age 82	Age 78	Age 75	Age 74
$750,000	Past 100	Age 92	Age 84	Age 80	Age 78
$1,000,000	Past 100	Past 100	Age 92	Age 86	Age 82
$1,500,000	Past 100	Past 100	Past 100	Age 98	Age 92
$2,000,000	Past 100	Past 100	Past 100	Past 100	Past 100

Pension and Social Security income

The other income box is for money that arrives every month in retirement without touching your savings: a pension from an employer, Social Security, or an annuity you already own. Enter it in today's money.

This calculator does not estimate your Social Security benefit, because the real figure depends on your own earnings record. The Social Security Administration works it out for you. A free my Social Security account at ssa.gov shows the benefit you could receive at different ages, and ssa.gov also has calculators you can use without signing in. A few facts from the SSA help when you choose a figure:

You can start retirement benefits at any time between age 62 and age 70.
The monthly amount is higher the longer you wait to start, up to age 70.
Full retirement age is between 66 and 67, depending on when you were born. It is 67 for anyone born in 1960 or later.
Starting at 62 with a full retirement age of 67 cuts the monthly amount by 30%.
Benefits are raised for increases in the cost of living, as measured by the Consumer Price Index.

The calculator raises your other income with inflation every year. That fits Social Security. Some pensions pay a fixed amount that does not rise. If yours is fixed, enter a lower figure to allow for that. If your other income starts later than your retirement age, the result will be too generous for the years in between.

Choosing your assumptions

Return before retirement. The default is 6% a year. It is a round number for illustration, not a prediction. Try 4% and 8% to see the range.
Return in retirement. The default is 4%. Set it to match how you expect to hold your money once you are drawing on it.
Inflation. The default is 2.5%. A higher figure shrinks the today's money result and makes the savings run out sooner.
How long to plan for. The SSA has a life expectancy calculator that gives an average from your sex and date of birth. It is an average, so many people live longer than the figure it gives.

What the result leaves out

Tax. Withdrawals from traditional retirement accounts are taxed as income, and part of a Social Security benefit can be taxed too. The spending figure here is treated as money taken out, not money left after tax.
Rising saving. The monthly saving is held at the same dollar amount until you retire. If you expect to save more as your pay rises, the result is on the low side.
Bad timing. The same return is used every year. Real returns vary, and losses early in retirement do more harm than the same losses later.
Changing costs. Spending is held level in today's money. Yours may rise or fall as you get older.
One-off sums. Selling a home, an inheritance or a large purchase is not included.
Fees. Enter returns after fees.

Common mistakes

Mixing today's money with future money. Enter spending and other income at today's prices. The calculator handles the rise in prices.
Leaving out Social Security completely. Entering $0 makes the picture darker than it is. Get your estimate from ssa.gov.
Planning to the average lifespan. An average means many people live longer. The calculator checks up to age 100 for that reason.
Using a high return to make the numbers work. A result that only holds at a high return leaves no room for poor years. Try a lower figure as well.
Forgetting tax. Spending $3,500 from a traditional account means withdrawing more than $3,500.

Questions people ask

How long will my retirement savings last?

It depends on four things: how much you have when you stop work, how much you take out each month, what the remaining money earns, and how fast prices rise. Enter your own figures above and the calculator gives the age the money runs out, or tells you it lasts past 100.

How much do I need to save for retirement?

There is no single number. Start from the monthly spending you want, take off any pension or Social Security income, and the rest has to come from savings for as long as you live. Raise the monthly saving in the calculator until the money lasts as long as you want it to.

How do I find my Social Security estimate?

This calculator does not estimate it. The Social Security Administration does, from your own earnings record, in a free my Social Security account at ssa.gov. It shows the benefit you could receive at different ages.

Should I enter amounts in today's money or future money?

Today's money. Enter the spending you would want at today's prices and the calculator raises it with inflation each year, both up to retirement and during it.

Why is the return in retirement lower than before retirement?

It is only a default, and you can set the two boxes to the same figure. They are separate because some people move to steadier investments once they start drawing on their savings, and steadier investments tend to earn less.

Does the result include tax?

No. Withdrawals from traditional retirement accounts are taxed as income, so you would need to take out more than you spend. To allow for that, add your expected tax to the monthly spending figure.

What if I want to retire early?

Lower the retirement age and watch two things change: fewer years of saving and more years of spending. Social Security retirement benefits can start as early as age 62, and the monthly amount is higher the longer you wait, up to age 70. If you retire before your other income starts, enter 0 for other income to see the harder case.

Sources

Figures last checked against these sources on October 10, 2026. This page gives general information and estimates, not tax, legal or financial advice.